Electronic coin tester with oscillator feedback sensing coil - evaluates half-wave rectified input or output using threshold circuit controlling sorters

摘要

The electronic coin tester passes coins through an alternating magnetic field of an oscillator coil. The oscillation variations are analysed using threshold circuits controlling sorters and/or generating pulses. It has higher checking resolution and is cheaper to manufacture than its commercially available alternatives. The oscillator is a LC push-pull type with two complementary amplifiers. The oscillator feedback impedance inductivity varies with the effect of the coins. The oscillator is asymmetric and has different input and output capacitances. One amplifier is connected to the operating voltage via a resistor and the other to earth. The oscillator gain is dependent on the operating voltage. The high frequency oscillator input or output voltage is half-wave rectified and evaluated.